The invention relates to a vibrator including a vibrating table with driven unbalanced shafts being disposed in the vibrating table and each being equipped with an unbalanced body. The unbalanced shafts are associated with one another in pairs and are provided with an adjustment device by means of which the vibrating frequency and the angular position of the unbalanced bodies relative to one another can be changed.
An adjustable and controllable vibrator of the mentioned type serves the purpose of optimally compacting concrete elements during their production. This is accomplished by program controlled adaptation of the operating parameters of the vibrator to the product specific requirements during the production process.
The following solutions are provided in the art for a program control: a mechanical adjustment of an unbalanced mass from the zero position up to a maximum value is effected in connection with external or counter-revolving vibrators in that transversely movable toothed clamps are disposed on the unbalanced shafts which are connected by way of a push rod equipped with oblique teeth with an adjustment device disposed outside of the vibrator (German Periodical "Betonwerk+Fertigteil-Technik" [Concrete Manufacture+Finished Component Technology] No. 10/1988, pages 48-50). Phase adjustment is possible by means of an electromechanically adjustable overriding drive (DE 3,708,922.A1); or by means of a phase adjustment drive (DE 3,709,112.C1).